On-chip implementation of multiprocessor systems requires the planarization of the interconnect network onto the silicon floorplan. Manual floorplanning approaches will become increasingly more difficult and ineffective as multiprocessor complexity increases. Compared with traditional ASIC architectures, multiprocessors have homogeneous processing elements and regular network topologies. Therefore, traditional ASIC .floorplanning methodologies based on macro placement are not effective in this domain. In this paper, we propose an automated physical planning tool, called REGULAY, that can generate floorplans for different topologies under different design constraints. Compared with traditional floorplanning approaches, REGULAY shows significant advantages in reducing the total interconnect wire-length while preserving the regularity and hierarchy of the network topology.